Recording stylus



' Dec. 9, 1941. y H,1 .'1ME| MANN v 2,265,601

RECORDING SITYLUs Filed Deo. 50,"1940 `Patented Dec. 9, 1941 UNITED STATES PATENT IOFF/ICE I2,265,601 RECORDING s'rrws Henry Louis Imelmann, Chicago, Ill., assignor to Permo Products Corporation, Chicago, lll., a corporation of Illinois Application December 3o, 1940, serial No. 372,298

(ci 27a-3s) 2 Claims.

My invention relates to recording styli, and is directed more particularly to a construction which aiords the use ofmore efcient manufacturing equipment, resulting in an improved stylus and in one which is cheaper to manufacture. One of the objects of my invention is to provide a stylus which may be manufactured by the use of more elcient grinding apparatus and grinding operations.

Another object of the invention is to provide a stylus construction which affords the use of a grinding lap .of increased size whereby the necessary grinding is completed much more easily, accurately, and efficiently.

Other objects and advantages of the invention will become apparent from the following speciilcation and accompanying drawing, in which:

Fig. 1 is a side elevation of the stylus as it is applied'l to the lap in a manner according to my invention; Fig. 2 is a side elevation of a modif-led form of the completed stylus:

Fig. 3 is a front elevation showing the leading face of the stylus; and

Fig. 4 is a front end elevation of the stylus.

Referring to the drawing, particularly to Figs. 1 and 3, it will be seen that the stylus includes a body portion Ill having a, dat I I ground thereon to facilitate the alignment thereof in the recording machine." The forward end of the stylus is formed to provide a pair of angularly disposed rear faces I2-VI2 and a forwardly disposed leading face I3 terminating in a pair of cutting edges I4, which edges form the junction betweenvthe faces -I2 'and the face I3.

In manufacturing the stylus the principal operation is that during which the faces are ground to their proper proportions, the vtolerance permitted in these proportions being extremely slight in order toV insure that the groove cut by the needle is one of proper proportion. speaking there are three grinding operations: the rst, a rough cut whereby the general configura'- tion is obtained; the second, a medium cut which constitutes a cut which lcarries the dimensions of the faces I2-I2, I3 to the proper proportions; and third, the finishing operation during which a minimum of material is takemfrom the stylus l and rather an' extremely high polish is obtained.

This last cut is for the purpose of sharpening they Generally tain the proper angle of the face I3 with respect to the longitudinal axis of the stylus, to cut away the shank material a considerable distance up the shank portion of the stylus.' This results in a weakening of the needle and has a serious detrimental effect on its mechanical properties. It has also been found in the past that withthe use of a lap having a smaller circumference. the working spot thereon has considerableA curvature due to the reduced diameter ofthe lap, and that under these conditions it is almost impossible to properly align the face of the stylus ona the circumferential edge of the lap to avoid grinding merely a portion of the leading face during the second and third operations, which face ofcourse has been previously formed during the rst grinding operation.

'Another disadvantage in styli of the straight type isv that in attempting to work them on a large lap it has been found that the chuck or tool actually engages the circumferential edge thereof and disrupts the entire grinding operation.

In order-therefore to utilize a larger lap and thereby gain the advantages rst of an extremely higher grinding surface speed, and second, a minimum of grinding away of the shank portion, the utilization of a relatively flat working spot due to increased diameter and increased circumference, and to be able to efciently grip theshank and avoid wearing of the chuck against the circumferential edge of the lap, I have eonstructeda stylus formed as-shown in Figs. 1 and 2.

As will be seen'from Fig. 1, all of the foregoing diiliculties are avoided by bendingv the stylus as at I5, whereby the shank is removed to a considerable degree from the working plane to permit. the utilization of a larger lap.

From past experience it has been found that when the smaller lap, made necessary by the straight shank, was used, considerable difficulty wasI encountered in aligning the leading face I3 edges I4 to such a degree that a clean cut is obtained in the material being worked upon.

It will be readily understood that should-a large lap be used to grind the leading face on the needle, it would be necessary, in order to ob 55 lap for the secondv and 4third operations. With the yconstruction shown in Fig. 1, however, and with the lap there shown, it is now found that the working spot on the lap, .that'is the area covered by the face I3 as it is being ground, is so small with respect to the enlarged curvature of the lap that this lworkingfspot has been ef Under these circumfectively flattened out. stances the worker has little or no difflculty in laligning lthe stylus for the second and third'op` erationsf and as a matter of fact the alignment now amounts to merely placingthe face against vthe circumferential edge of the lap. With the present construction the examination of a large amount o! needles made in this way has revealed that the grinding on the second and third operations has covered the entire face I3, and there are no longer partial grindings wherein certain spots on the needle have been missed by the lap in the second and third grinding operations due to the extreme curvature of the working spot'on the lap.

The modifi-ed form of stylus shown inv Fig. 2 l0` embodies the same principles heretofore described. However, the shank I0" is not integral with the stylus portion l1 upon which the faces i2"|2'.' and I3" are ground. The shank l0" has a longitudinal bore I8 therein, into which the portion l1. is placed, whereupon the shank is swedged as at I9 to retain the portion I1 within the shank. The portion i1 is similarly bent as at 20.

Having thus ldescribed my invention what I claim as new and desire to secure by United States Letters Patent is:

1. As a. new article oimanufacture. a record ,ing stylus, said stylus having a shank portion for a portion having cutting means for engaging the i material to be cut, said shank portion and said portion having the cutting means being disposed angularly to one another, said cutting means including a leading face all points of which are outside of a circumferential plane'dened by 20 said shank portion. y

HENRY LoUIs' mELMANN. 

